i4 Diorites and Granites of Swifts Creek, 



colony, near Cape Howe, westward through Gippsland, at an 

 elevation of from 700 to 800 feet, it would define approxi- 

 mately the upper limit of the marine tertiaries ; or, in other 

 words, the maximum level in respect to the mountain mass 

 at which the sea has stood during Cainozoic time, or still 

 more properly, it would represent the total elevation of the 

 land above sea-level during that period. But in the latter 

 case it would be necessary to add to that elevation of 700 or 

 800 feet also the depth at which the continuation of the 

 older leads would, if traced out, emerge below the level of 

 the sea. An extension of such a contour line round the 

 northern slopes of the mountains would also define similar 

 features in the Murray basin, where, however, the condi- 

 tions were probably lacustrine. It is of interest to observe 

 that this same contour line would also approximately mark 

 a zone within which the flora — as, for instance, species of 

 eucalyptus — differ from those met with at higher levels. 

 From this upper margin of the marine tertiaries rise the 

 first tiers of mountains composed of palceozoic rocks. Higher 

 again than these commence the elevated plateaux — such as 

 Omeo and Gelantipy, in which the rocks are mainly 

 palceozoic, but are also in places Tertiary volcanic. The 

 vegetation of these plateaux approaches an alpine character ; 

 the country is generally open and well grassed, and, again, 

 marked by peculiar species of eucalypti. The grassy 

 character of the country becomes still more predominant in 

 ascending to greater elevations, until at about 5000 feet 

 above sea-level the eucalyptus forests cease, and the highest 

 plateaux and mountain summits are thickly clothed with 

 snow-grass and alpine plants. 



These mountain plateaux are a peculiar feature of the 

 Australian Alps. An extended examination has shown me 

 that they are the remains of a once vast tableland which 

 stretched from Victoria far round the eastern coast of 

 Australia, and the width of which in this colony may be 

 roughly defined by Mount Wellington in the south and 

 Mount Buffalo in the north. Leaving out of consideration 

 smaller tracts — such as the summit of Mount Useful — it is 

 evident that the high plains of Wonnangatta, the Dargo, 

 and the Bogong, the tablelands of Omeo, Nunnyong, and 

 Gelantipy, are connected by similar physical features, eleva- 

 tion, climate, and vegetation with the extensive plateau of 

 Maneroo. These remarks, when somewhat modified, are 

 equally applicable to the northern slopes of the mountains 



